The present invention relates to a process for the continuous production of alkali metal salts of fatty acids.
Alkali metal salts of fatty acids, or what are commonly known as soaps, can be obtained from fatty acid esters of glycerine or from fats or from fatty acids by reaction with alkali metal hydroxides. There are several known batch-type processes and continuous processes for the production of soaps. The batch-type processes are generally carried out at boiling point in an open stirrer-equipped vessel. In the case of the continuous processes, saponification in closed vessels has already been successfully applied in some cases, especially since it provides for a considerable reduction in energy costs. However, the known processes, including the continuous process, are still attended by serious disadvantages. Not only do the products obtained have a very high water content due to the fact that saponification is carried out in emulsion, the water having to be removed by evaporation. (in some cases even in vacuo,) but also by the fact that the aqueous phase which accumulates during centrifuging of the soap emulsion also has to be worked up. Both process steps involve (in some cases serious) effluent problems and, in addition, are also costly in regard to the energy required for working up.
Accordingly, there was a genuine need to develop a process for the production of alkali salts of fatty acids which not only can be carried out continuously using reaction components present in concentrated form, but also yields end products which do not require any further drying.